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Figure 3
(a) Linearity of C10158DK. After averaging five diffraction images of a CaSO4·2H2O powder pattern to improve S/N, the dark current was subtracted. The intensity of one pixel for the 020 reflection was plotted against the photon flux of the incident X-ray beam. (b) Horizontal profile of the flat-field image. After averaging 100 raw images, the dark-current image was subtracted. Average profiles of the central 264 rows are shown. The incident X-rays travelled from the left side to the right side in this figure. A gradual change in intensity with the pixel position can be explained by the absorption of the incident X-rays and fluorescence X-rays by the NaBr solution; the fluorescence X-rays emitted from different points on the incident-beam path decrease gradually along with the incident beam because the incident X-ray is reduced by absorption. In addition, the intensity of the fluorescence X-ray is asymmetrically attenuated by the absorption and has a different intensity depending on the direction, unless it was emitted from the centre of the capillary. Therefore, convolution of the intensity of fluorescent X-rays emitted from multiple points generates an asymmetrically gradually changing profile. Calculation of the intensity profile considering the effect of absorption generates almost the same profile (data not shown).

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